Catalytic effect of silver addition on the low temperature phase formation of MgB2

A small amount of silver addition was found to dramatically decrease reaction temperature of magnesium and boron forming the MgB2 bulk without degradations in both critical temperature and critical current properties. A sample with ∼3% silver addition for magnesium heated at 550 deg. C for 72 h recorded a high Jc above 2 x 105 A cm-2 at 20 K in low fields reflecting its strongly grain-coupled microstructure. In addition, a sample with ∼5% silver addition showed Jc of ∼1 x 105 A cm-2 at 20 K in low fields even for heating at 500 deg. C for 72 h. Although the added silver formed Ag-Mg alloy after the heat treatment, these impurity particles mainly existed at the edge of voids without losing the effective current path. Our present results will contribute to developing low cost MgB2 conductors